[Freeswitch-users] SDP with 2 m=audio lines

[Anthony Minessale]

The word undefined does not even appear in that RFC.

RFC 2327 (the one that actually describes SDP) is the relevant one:

" A session description may contain a number of media descriptions.
   Each media description starts with an "m=" field, and is terminated
   by either the next "m=" field or by the end of the session
   description.  A media field also has several sub-fields: "


The ptime attribute cannot be applied to a single codec mentioned in a
m= line it must apply to all of them.
Once you have 2 different ptimes in the same description you have no
choice but to split it into different m= lines for each sep ptime.

If you dislike this behavior then set:

sdp_m_per_ptime=false

either globally in vars.xml or in your dialplan on a per leg basis.







On Tue, Feb 14, 2012 at 7:39 AM, Sergey Okhapkin
<sos at sokhapkin.dyndns.org> wrote:
> I noticed that recent freeswitch versions could send SDP with 2 m=audio lines.
> Per RFC 3388, the behavior is undefined this case. I don't know how to
> reproduce the problem, I see such packets coming from my customers. Here is an
> example:
>
> INVITE sip:xxxxxxxxxxxx at sip.callwithus.com SIP/2.0
> ...
> User-Agent: FreeSWITCH-mod_sofia/1.0.head-git-eeeaf41 2012-02-10 17-27-50 -0600
> ....
>
> v=0
> o=FreeSWITCH 1329167961 1329167962 IN IP4 xx.xx.xx.xx
> s=FreeSWITCH
> c=IN IP4 xx.xx.xx.xx
> t=0 0
> m=audio 24598 RTP/AVP 0 101 13
> a=rtpmap:101 telephone-event/8000
> a=fmtp:101 0-16
> a=ptime:30
> m=audio 24598 RTP/AVP 98 0 8 3 101 13
> a=rtpmap:98 SILK/8000
> a=fmtp:98 useinbandfec=1; usedtx=0
> a=rtpmap:101 telephone-event/8000
> a=fmtp:101 0-16
> a=ptime:20
>
>
> Hmm, I just realized that this SDP is buggy - 2 audio streams on the same
> port, with common codecs, but with different ptime :-)
>
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-- 
Anthony Minessale II

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